This application claims the priority of German application 100 26 449.2, filed May 27, 2000, the disclosure of which is expressly incorporated by reference herein.
This invention refers to a trochoidal design rotary piston engine with a rotary piston housing, two side disks, one of the eccentric shafts bearing-mounted in the side disks, a rotary piston, and an eccentric cam bearing-mounted eccentric shaft with a pressure oil supply unit for supplying oil to the side disk, the bearings and the rotary piston bearing of the eccentric shaft.
Many models of the above-noted rotary piston engine designs are known, for example, from the German Pat. Document No. DE-C 40 03 663 (corresponding U.S. Pat. No. 5,199,863) and are also being serially produced. These types of engines are generally equipped with a fluid cooling system necessary for the peripheral heat exchangers and lines. This supplemental equipment and the cooling fluid will nearly double the total weight of the unit compared to a net engine weight. With the known weight optimizing construction with a performance range of up to approximately 100 kW, the system specific weight is approximately 1 kg/kW or better. A reduction in the system specific weight would be desirable for the use of such engines in aviation operations. Additionally, a demand on the modern engines, in addition to a high specific performance is also a highest possible efficiency. Furthermore, the possibility of supercharging the engine for multi-fuel operations should be available, especially in the shift charging process. This supercharging leads to increased combustion chamber pressures and is linked to high local temperature loading. A weight favorable air-cooling by itself could not meet these demands.
An object of this invention is to accomplish the task of producing an above-described rotary piston engine with lowest possible specific system weight ratio.
This object has been achieved according to preferred embodiments of the invention in that the pressure oil supply system splits the low pressure line leading to the side disks and rotary piston housing cooling channels which are connected to the re-circulation of the pressure oil supply system.
According to certain preferred embodiments of this invention, the bearing lubrication and the pressure oil needed for the cooling of the piston is also used to cool the rotary piston housing and the side disks. That saves on the need for a coolant cooling separator with attendant lines so that the system weight can be reduced accordingly.
It has been foreseen in certain preferred embodiments of the invention design that the low-pressure line would be connected to both side disks whose cooling channels are linked to the axial cooling channels of the rotary piston housing. Thus it has been advantageously anticipated that the side disks cooling channels will be designed in such a way that the oil supplied to one side disk will be delivered, after flowing through the cooling channels of the rotary piston housing, to the other side disk. That provides for a very effective cooling of the side disks and the rotary piston housing.
In a further design feature of certain preferred embodiments of the invention, it is intended that the rotary piston housing will have an angle range of about 90 degrees in the direction of the motion toward the exhaust pipe and is equipped with axial cooling channels. In the practice, it will mostly suffice to cool only this area with oil, since it is subjected to the highest heat load.
For practical purposes, it is provided in certain preferred embodiments of the invention that the pressure oil supply system will include an oil pump with at least twice the capacity requirements of the oil quantity required for lubrication of the bearings. That ensures that a sufficiently large quantity of cooling oil will be supplied by the low-pressure branch of the oil cycle.
In order to further reduce the engine load, it has been additionally established according to certain preferred embodiments of the invention that the rotary piston housing would be equipped with cooling ribs over an angular range of about 90 degrees in the direction of the motion toward the exhaust pipe.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.